As a light source used for a projection-type display apparatus such as a projector, an ultra-high pressure mercury vapor lamp is mainly used from the viewpoints of brightness and cost performance, but a solid state light source having a long lifetime and a wide color range is drawing attention from the viewpoints of long lifetime characteristics, high functionality addition, etc. The solid state light source is a light source using a light emission phenomenon based on a p-n junction of semiconductors, and is typified by an LED, a laser (LD), and the like. These days, a light source apparatus in which a solid state light source is used to apply light to a phosphor material that, when irradiated with light in a specific wavelength range, emits light in a wavelength range different from the wavelength range of the applied light and the fluorescently emitted light is utilized is used for a projector and the like.
Such a light source apparatus includes a phosphor wheel on a surface of which a phosphor layer is formed and a solid state light source that emits excitation light. The light emission of the phosphor has the phenomena of luminance saturation and thermal quenching. This is an event in which, when the power of excitation light is increased, part of the conversion loss in the phosphor changes to heat and the phosphor generates heat, and consequently the efficiency of fluorescent emission is reduced. A bright light source apparatus with good efficiency cannot be obtained in the state where the fluorescence conversion efficiency is low. Hence, a technology in which a heat sink is attached to the phosphor wheel to improve the heat dissipation efficiency is proposed.
For example, Patent Literature 1 discloses a technology in which, in a color wheel in which a phosphor area for each of red, green, and blue is formed and that emits red light, green light, and blue light as fluorescence upon irradiation with excitation light, a heat dissipation unit is formed on the surface on the opposite side to the surface on which excitation light is incident. Further, Patent Literature 2 discloses a phosphor wheel in which, for a phosphor applied to a surface of a substrate, a heat sink is adhered to at least one of the inside and outside in the radius direction with respect to the phosphor so as to avoid the optical path of the light transmitted through the phosphor.